In the technique of packaging a chip component on a printed circuit board, a method which uses a solder bump and a method which connects a bump and a substrate terminal using one out of an electrically conductive adhesive, an anisotropic conductive film (ACF) and a non-conductive film (NCF), is currently in use. Of these methods, the connecting method which uses the ACF or NCF is not in need of an underfill process which is necessary in case of using the solder bump or the electrically conductive adhesive. The reason is that, in the connecting method which uses the ACF or the NCF, a chip component is packaged after it is temporarily attached by pressure bonding to the substrate. Hence, the connecting method which uses the ACF or NCF is used for larger numbers of semiconductor packages employed in electronic equipment (see Patent Publication 1 by way of an example).
Recently, not the mechanical contact with the ACF but rather the connection by metallic bond with the NCF is thought to be desirable in view of bump-land connection reliability. However, since the conventional NCF uses an epoxy resin composition which uses imidazoles as a curing agent, the reaction of curing initiation becomes faster, with the consequence that sufficient connection reliability may not be achieved.
On the other hand, the NCF is thought to be desirably transparent in view of ease in visually checking an alignment mark at the time of bonding the film on the printed circuit board. However, if a curing agent other than imidazoles is used, it is difficult to obtain a transparent epoxy resin composition, thus occasionally leading to a turbid composition. It is thought that a sea island structure unit, formed in a binder, may be responsible for the composition thus becoming turbid.